user-interface designers, to explore and/or validate the user-interface design before too much is invested
in it

requirements specifiers, to understand the user interface for a Use Case

system analysts, to understand how the user interface impacts the analysis of the system

designers, to understand how the user interface impacts and what it requires from the "inside" of the system

managers, to plan development and testing activities

User-Interface Prototypes can be used to explore an achievable and suitable user-interface design that fulfills the
requirements, helping to close the gap between what is required (expressed through requirements elicitation) and what
is feasible. The main purpose of creating a user-interface prototype is to be able to "test out" the user-interface
design, including its usability before the real development starts. This way, you can ensure that you are building the
right system, before you spend too much time and resources on development.

User-Interface Prototypes may be formal or informal, executable or non-executable, low fidelity or high-fidelity
prototypes. For example, a User-Interface Prototype may range from a series of pictures represent screen captures of
some interactive HTML pages. The format the UI prototype takes is not the issue. What is important to keep in mind is
the purpose of the User-Interface Prototype (to explore and/or validate a user-interface design), and what skills are
required to produce the prototype (a User-Interface Prototype requires some user-interface design skills).

Decide whether a prototype is suitable for your project. Decide on how much of the user interface to prototype,
and the depth and realism of any interactivity. Decide whether the prototype is purely throwaway, or whether some
aspects are intended to evolve into the end product.

Keep in mind that in order to achieve the goal of early testing of the user interface, the prototype must be
significantly cheaper to develop than the real system, while having enough capabilities to be able to support a
meaningful use test.